To get the oil varnish film off the inside surfaces of engine parts, e.g. valve covers/timing covers, Purple Power is the bee's knees. That stuff is awesome. It works way better for this job than Stoddard Solvent (aka mineral spirits) or brake cleaner. Brake cleaner works good but it evpaorates too fast and you get asphyxiated or a buzz while doing it. I discovered this by accident. I worked and worked using brake cleaner to get the varnish off the inside surface of my front timing cover on my 104 motor. I set the cover aside on the bench to take a break and in so doing I accidentally spilled some Purple Power on it and the varnish just started running off. Yeah! Plus you can wash it off with water. Spray down the part, let it sit five minutes, and wash away all that friggin varnish. Sweeeeeet.

Time for a show of hands of all you who've gotten busted by Momma for cleaning grungy engine parts in the kitchen sink ;-)